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From B. Lee Clay


 Squaring Numbers

 Multiplying Numbers

 Dividing Numbers

  1. any by 0.125
  2. 2 digits by 1 1/9
  3. 2 digits by 1 1/8
  4. 2 digits by 1 1/7
  5. 2 digits by 1 1/6
  6. 2 digits by 1 1/5
  7. 2 digits by 1 1/4
  8. 2 digits by 1 2/7
  9. 2 digits by 1 1/3
  10. 2 digits by 1 2/5
  11. 2 digits by 1 3/7
  12. 2 digits by 1 1/2
  13. 2 digits by 1 3/5
  14. 2 digits by 1 2/3
  15. 2 digits by 1 3/4
  16. 2 digits by 1 4/5
  17. 2 digits by 2 2/9
  18. 2 digits by 2 1/4
  19. 2 digits by 2 1/3
  20. 2,3 digits by 2 1/2
  21. 2 digits by 2 2/3
  22. 2 digits by 2 6/7
  23. 2 digits by 3 1/8
  24. 2,3 digits by 3 1/3
  25. 2 digits by 3 1/2
  26. 2 digits by 3 4/7
  27. 2 digits by 4 1/6
  28. 2 digits by 4 2/7
  29. 2 digits by 4 4/9
  30. 2 digits by 4 1/2
  31. 2 digits by 5
  32. 2 digits by 5 5/7
  33. 2 digits by 6 1/4
  34. 2 digits by 6 2/3
  35. 2 digits by 7 1/7
  36. 2 digits by 7 1/2
  37. 2 digits by 8 1/3
  38. 2 digits by 8 4/7
  39. 2 digits by 12 1/2
  40. 2 digits by 15
  41. 2,3 digits by 16 2/3
  42. 2,3 digits by 25
  43. 2,3 digits by 33 1/3
  44. 2,3 digits by 35
  45. 2 digits by 37 1/2
  46. 2 digits by 40
  47. 2 digits by 45
  48. 2 digits by 50
  49. 2 digits by 62 1/2
  50. 2 digits by 66 2/3
  51. 2,3 digits by 75
  52. 2 digits by 83 1/3
  53. 2 digits by 87 1/2
  54. 2 digits by 125
  55. 2 digits by 166 2/3
  56. 2 digits by 250
  57. 2,3 digits by 333 1/3
  58. 2 digits by 375
  59. 2 digits by 625
  60. 2 digits by 875
  61. 3 digits rep./37+41
  62. 6 digits rep. by 15873
  63. 6 digits rep. by 7, then 13
  64. 6 digits rep. by 13, then 11
  65. 6 digits rep. by 7,11,13, subtract 101
  66. 6 digits rep. by 37037 x 5
  67. mixed numbers by 2
  68. diff. of squares of 2 consec. 2-digit numbers
  69. diff. of squares of 2 different 2-digit numbers
  70. sqrt of squares of 2-digit numbers ending in 1
  71. sqrt of perfect squares ending in 5

 Adding Numbers

 Subtracting Numbers

 Finding Percents

Calculation
Practice Exercises

Full List



   Dividing a repeating 6-digit number by 7,
                then by 13

  1. Select a 3-digit number.
  2. Repeat these digits to make a 6-digit number.
  3. Divide these 6 digits by 7, then by 13.
  4. The answer is 11 times the first three digits!

   Example:

  1. If the 3-digit number selected is 234:
  2. The 6-digit number is 234234.
  3. Divide by 7, then by 13: multiply by 11
    - to multiply 234 by 11, work right to left:
    last digit on right = _ _ _ 4
    next digit to left = 3 + 4 = 7: _ _ 7 _
    next digit to left = 2 + 3 = 5: _ 5 _ _
    last digit on left = 2 _ _ _
  4. So 234234 divided by 7, then 13 is 2574.

   See the pattern?

  1. If the 3-digit number selected is 461:
  2. The 6-digit number is 461461.
  3. Divide by 7, then by 13: multiply by 11
    - to multiply 461 by 11, work right to left:
    last digit on right = _ _ _ 1
    next digit to left = 6 + 1 = 7: _ _ 7 _
    next digit to left = 4 + 6 = 10: _ 0 _ _
    last digit on left = 4 + 1(carry) = 5: 5 _ _ _
  4. So 461461 divided by 7, then 13 is 5071.

Practice multiplying by 11 - this process works for multiplying any number by 11.


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25 November 1996
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